1. Field of the Invention
The invention relates to improvements in push-button lock arrangements which arrangements include a permutation chamber. More specifically, the invention relates to such an arrangement wherein the combination of the permutation chamber can be changed, when the permutation chamber is mounted in an assembled such arrangement, without dismantling the arrangement and without the use of special tools.
The invention also relates to such an arrangement in which the permutation chamber shaft is constrained to a predetermined angle of rotation, the novel arrangement including means for constraining the rotation of the outside door knob to the same angle of rotation.
2. Description of Prior Art
Permutation chambers for combination locks are well known in the art as illustrated in, for example, U.S. Pat. No. 3,115,765 Fengler, Dec. 31, 1963. In order to change the combination of such a permutation chamber, the present combination is first inserted, and then the end 88 of the lock-out plate 44 (see FIG. 2 of the patent) is pushed inwardly. The new combination is then inserted, and the lock-out plate is then returned to its original position by rotating the input shaft 29.
Also known in the art are combination locks with means for changing the combination. Such combination locks are illustrated in, for example, U.S. Pat. No. 4,748,833, Nagasawa, June 7, 1988, U.S. Pat. No. 4,827,743, Kim, May 9, 1989 and U.S. Pat. No. 4,027,508, McGourty, June 7, 1977.
In the Kim patent, a combination change mechanism is illustrated at 135 in FIGS. 5 and 6. Referring to FIG. 6, the reset assembly includes a plurality of combination setting imposers 153. It can easily be seen that in order to reset the combination in this combination lock, the entire lock must be taken apart.
The Nagasawa patent teaches a combination lock which does not appear to use gears. Instead, it uses a plurality of "keys" illustrated in FIG. 3 of the patent. The procedure for resetting the combination is described at column 6, lines 10 et seq. of the patent. As can be seen, one of the first steps is to remove the block 11 (see FIG. 1 of the patent). Thus, once again, the lock must be taken apart in order to reset the combination.
Although the McGourty combination lock does not have to be dismantled in order to reset the combination, it is noted that the McGourty combination lock does not include a permutation chamber. In accordance with the McGourty patent, a new combination is inserted by first rotating combination change key (see FIG. 3). When the key is rotated, reset slide 58 is lifted from the position shown in FIG. 14 of the patent to the position shown in FIG. 15 of the patent. With reset slide 58 lifted, gears 65 are disengaged from gears 31 and gear 70 is disengaged from gear 42. In this position, a new combination can be entered. As above-mentioned, the McGourty combination lock does not include a permutation chamber. Accordingly, the McGourty patent is not directed at subject matter similar to the subject matter of the present application.